I. Field of the Disclosure
The technology of the disclosure relates generally to circuits and related systems and methods to monitor a power supply voltage coupled to a functional circuit.
II. Background
Circuits such as central processing units (CPUs) or digital signal processors (DSPs) require power to operate. In this regard, a power supply provides a supply voltage to the circuit. During normal operation of a circuit, a power supply may undergo a supply voltage droop. A power supply voltage droop is a temporary drop or reduction in a power supply voltage being supplied by a power supply. Such behavior may be associated with a switching power supply. Reasons for a power supply voltage drop may include an increase in power supply current supplied by the power supply, a drop in supply voltage being provided to the power supply, an operational change to the power supply, the like, or any combination thereof. The increase in power supply current may be as a result of changes in the power supply and changes in a load receiving the power supply current.
For example, in a CPU that is supplied power from a switching power supply and is executing instructions, typical current consumption may be on the order of tens of milliamps (mA). However, if the CPU executes back-to-back hardware multiplies, current consumption may peak at about one (1) amp (A), thereby causing a supply voltage droop. As long as the voltage droop does not cause the voltage level provided by the power supply to the CPU to be below the minimum acceptable operating voltage of the CPU, the CPU continues to function properly. The difference between the power supply voltage provided to compensate for voltage droops and the minimum acceptable operating voltage of a circuit is the operating margin of the power supply voltage. The operating margin represents additional voltage that must be supplied to the circuit to assure proper circuit operation when power supply voltage droop events occur.
If the magnitude of a power supply voltage droop could be decreased or the effects of power supply voltage droop events could be mitigated, the operating margin could be reduced.